The invention relates to a ball bearing with sealing means and/or play-free positioning, preferably comprising an inner bearing ring or a shaft provided with raceways, an outer ring, and balls rolling between the bearing rings or between the shaft and the outer ring, respectively. The ball bearing also includes an outer sleeve which serves as a housing for the outer ring. The bearing must be suited for both low and high speeds, and is adapted to be used in applications where misalignment, shock loads or the like may occur.
In a prior-art design of a ball bearing, adapted for haulage-wheels and other bearings where great precision is not required and which may even be exposed to considerable fouling, the outer ring is in the form of a substantially cuplike hemispherical shell. This known cuplike hemispherical shell forms an inner space, in combination with a separate side ring, punched out of sheet metal, and a solid inner ring. A track is provided in this interior space, for receiving the rolling elements. The parts forming the outer ring of the bearing are held together by a sheet-metal cap having a steplike chamber into which a sealing ring is set. This ball bearing, which is used in less critical applications, is unsuited for use with electrical machinery such as motors or generators, in which noise or other vibrations are undesired. Also it cannot be relied upon to function properly for a prolonged period.
In a known design of a play-free ball bearing, a positioning ring is disposed between a ring which abuts on a ball guide ring and a retaining ring that is held in a groove in the bore of the outer bearing ring. This positioning ring urges the ball guide ring and the rolling elements against a fixed shoulder on the inner ring. In this arrangement, the positioning requires the use of many separately fabricated parts and thus represents a costly unit. No provision is incorporated for sealing the bearing.
The present invention is therefore directed to the provision of a ball bearing which can be produced inexpensively, yet may be used as a precision bearing, it being possible to convert it in a simple manner, merely by replacing one of the parts. The bearing thus comprises a basic unit which can be adapted readily to make a sealed or unsealed axially locating bearing, an axially preloaded bearing or a sealed and axially preloaded bearing.
The ball bearing in accordance with the invention is thus useful, for example, as a bearing for the rotor shaft of electrical machinery, such as a vacuum-cleaner motor, with the locating bearing constituting a complete bearing unit, and the non-locating bearing on the commutator side also being set into the bearing bracket as a complete, axially adjusted or preloaded bearing unit. In an electric motor equipped with the bearing in accordance with the invention, low-noise operation may be achieved by providing for axial adjustment or preloading of both rotor bearings by means of the mounting screws of the bearing brackets, the outer sleeves of both bearings being set into the bearing brackets with a firm fit. Axial displaceability of the rotor-shaft bearing is obtained at the outer ring of the axially non-locating bearing, which is set into the outer sleeve so as to be axially displaceable, and by the use of an axially preloaded adjusting spring. Jamming of the antifriction bearings is thereby precluded.